1. Field of the Invention
The invention relates to a flexible printed circuit board (FPC) for liquid crystal display (LCD) module, more particularly to a FPC with an extensible element for LCD module. It can be used in the different LCD modules to achieve the purpose of simplifying manufacturing process because the extensible element can be extended when it is applied a force.
2. Description of the Prior Art
While the science and technology evolved frequently, the display technology and the monitor played a very important role in the development process of the information technology. The portable devices and the display panel incorporated into each electric apparatus or meter, such as the computer, television, mobile phone, BP, and PDA (Personal Digital Assistant), provided large information in our daily life and work. Especially, the LCD (liquid crystal display), which has many advantages such as the low power consumption, low radiation, slim body and better display quality, becomes the main product in the plain display market.
As illustrated in FIG. 1, a LCD module 10, which uses the LED (Light Emitting Diode) as the light source, comprises a LCD panel 110, a LED back light source 120, a light source connecting FPC (flexible printed circuit board) 130, a panel connecting FPC 140, a connector 150 and a PCB (print circuit board) 160. The light source connecting FPC 130 connects the panel connecting FPC 140 via the connector 150. However, in consideration of the reliability and the thickness, another method to connect the light source connecting FPC 130 and the panel connecting FPC 140 on the PCB 160 is achieved by a bonding or a soldering process, so as to spare the space for the connector 150. Please refer to FIG. 2, the light source connecting FPC 130 and the panel connecting FPC 140 is mounted on the PCB 160 by the bonding or soldering process. One end of the light source connecting FPC 130 is connected with the back light source 120 and one end of the panel connecting FPC 140 is connected with the LCD panel 110, and the other ends of the both should be positioned and exactly connected to the PCB 160 by proper tools (not shown in FIG. 2). Then, the light source connecting FPC 130 and the panel connecting FPC 140 are turned over to the reverse side of the LED back light source 120. Due to the different radiuses of these two FPCs, it is resulted in one protruding length (L′) on the light source connecting FPC 130 other than the panel connecting FPC 140 as illustrated in FIG. 2. The circuit on the light source connecting FPC 130 can supply the power to the LED back light source 120, and the circuit on the panel connecting FPC 140 can transmit signal to control the LCD panel 110. The above back light source 120 uses the LED as the light source. In fact, the light source for the back light source 120 can also be CCFL (Cold Cathode Fluorescent Lamp) or other similar luminous components.
Because a FPC has flexibility and can be curved to a predetermined shape without damaging itself and the circuit thereon, it is used to serves as the light source connecting FPC 130 and the panel connecting FPC 140. Please refer to FIG. 3, three FPCs 310, 320, 330 in different size but with same circuit layout are shown for being applied to different types of LCD modules 31, 32, 33. One end of the FPC 310/320/330 is connected to a LCD panel 312/322/332 and the other end of the FPC 310/320/330 is soldered to a pad 314/324/334 on the PCB (not shown in FIG. 3). It increases the complication of preparing the material and the space of storing the FPC. Sometimes, the shape of the FPC must be redesign once the position of the pad on the PCB is changed. As illustrated in FIG. 4, the shape of a FPC 410 is redesign to the shape of a FPC 420, there being same circuit layout thereon, in order to be applied to the condition that the position of the pad on the PCB is changed. It not only spends time but also wastes resource to design different FPC shapes for different LCD modules. Therefor, we need a FPC with same circuit layout to be directly applied to different LCD modules.